Otto's Majestic Musical Number

7th-Level Enchantment Spell (Bard, Wizard)

Casting Time: Action
Range: Self
Components: V, M (a musical instrument)
Duration: Concentration, up to 1 minute

For the duration of the spell, you play a song on your instrument, and all creatures that can hear you must dance along. This does not limit their movement or actions they can take in any way, except they will do everything while dancing and singing along fabulously, to the best of their abilities.

When you cast this spell, the DM must designate an opposing dancer on the other side of the conflict. On initiative count 20 of the next round, and each round thereafter, you and the opposing dancer must make opposed Charisma (Performance) checks. The winner's side makes all attack rolls with advantage, and all attack rolls made against them are made with disadvantage. This effect lasts until this opposed Charisma (Performance) check is made again, or the spell ends.

If the opposing dancer is killed, the DM will designate a new opposing dancer for the check. If there are no more enemies affected by the spell, the spell ends. The DM may choose a different opposed skill check for one or both dancers, at his discretion.

Source: Homebrew